#define _CRT_SECURE_NO_WARNINGS  1

#include "snake.h"

void SetPos(short x,short y)
{
	//获得标准输出设备的句柄
	HANDLE houtput = NULL;
	houtput = GetStdHandle(STD_OUTPUT_HANDLE);

	//定位光标的位置
	COORD pos = { x,y };
	SetConsoleCursorPosition(houtput, pos);
}

void WelcomeToGame()
{
	SetPos(40, 14);
	wprintf(L"欢迎来到贪吃蛇小游戏\n");
	SetPos(42, 20);
	system("pause");
	system("cls");
	SetPos(25, 14);
	wprintf(L"用↑ ↓ ←  → 来控制蛇的移动，按F3加速，F4减速\n");
	SetPos(25, 15);
	wprintf(L"加速能够得到更高的分数\n");
	SetPos(42, 20);
	system("pause");
	system("cls");
}

void CreateMap()
{
	//上
	int i = 0;
	for (i = 0; i < 29; i++)
	{
		wprintf(L"%lc", WALL);
	}
	//下
	SetPos(0, 26);
	for (i = 0; i < 29; i++)
	{
		wprintf(L"%lc", WALL);
	}
	//左
	for (i = 1; i <= 25; i++)
	{
		SetPos(0, i);
		wprintf(L"%lc", WALL);
	}
	//右
	for (i = 1; i <= 25; i++)
	{
		SetPos(56, i);
		wprintf(L"%lc", WALL);
	}

}

void InitSnake(pSnake ps)
{
	pSnakeNode cur = NULL;
	for (int i = 0; i < 5; i++)
	{
		cur = (pSnakeNode)malloc(sizeof(SnakeNode));
		if (cur == NULL) {
			perror("InitSnake():malloc()");
			return;
		}
		cur->x = POS_X + i * 2;
		cur->y = POS_Y;
		cur->next = NULL;
		if (ps->_pSnake == NULL) {
			ps->_pSnake = cur;
		}
		else {
			cur->next = ps->_pSnake;
			ps->_pSnake = cur;
		}
	}
	cur = ps->_pSnake;
	while (cur)
	{
		SetPos(cur->x, cur->y);
		wprintf(L"%lc", BODY);
		cur = cur->next;
	}

	//设置贪吃蛇的属性
	ps->_dir = RIGHT; //默认向右
	ps->_score = 0;
	ps->_food_weight = 10;
	ps->_sleep_time = 200; //单位是毫秒
	ps->_status = OK;
}

void CreateFood(pSnake ps)
{
	int x = 0;
	int y = 0;
	//x：2-54  x是2的倍数
	//y：1-25
again:
	do {
		x = rand() % 53 + 2;
		y = rand() % 25 + 1;
	} while (x % 2 != 0);

	//x和y的坐标不能和蛇的身体坐标冲突
	pSnakeNode cur = ps->_pSnake;
	while (cur)
	{
		if (x == cur->x && y == cur->y) {
			goto again;
		}
		cur = cur->next;
	}

	//创建食物的节点
	pSnakeNode pfood = (pSnakeNode)malloc(sizeof(SnakeNode));
	if (pfood == NULL) {
		perror("CreateFood():malloc()");
		return;
	}
	pfood->x = x;
	pfood->y = y;
	pfood->next = NULL;

	SetPos(x, y);
	wprintf(L"%lc", FOOD);

	ps->_pFood = pfood;
}

void GameStart(pSnake ps)
{
	//初始化游戏
	//0.先设置窗口的大小，再隐藏光标
	system("mode con cols=100 lines=30");
	system("title 贪吃蛇");
	HANDLE houtput = GetStdHandle(STD_OUTPUT_HANDLE);
	CONSOLE_CURSOR_INFO CursorInfo;
	GetConsoleCursorInfo(houtput, &CursorInfo);
	CursorInfo.bVisible = false;
	SetConsoleCursorInfo(houtput, &CursorInfo);
	//1. 打印环境界面
	//2. 功能介绍
	WelcomeToGame();
	//3. 绘制地图
	CreateMap();
	//4. 创建蛇
	InitSnake(ps);
	//5. 创建食物
	CreateFood(ps);
}

void PrintHelpInfo()
{
	SetPos(64, 14);
	wprintf(L"%ls", L"不能穿墙，不能咬到自己");
	SetPos(64, 15);
	wprintf(L"%ls", L"用↑ ↓ ←  → 来控制蛇的移动");
	SetPos(64, 16);
	wprintf(L"%ls", L"按F3加速，F4减速");
	SetPos(64, 17);
	wprintf(L"%ls", L"按ESC退出游戏，按空格暂停游戏");

}

#define KEY_PRESS(vk) ((GetAsyncKeyState(vk)&1)?1:0)

void Pause()
{
	while (1)
	{
		Sleep(200);
		if (KEY_PRESS(VK_SPACE)) {
			break;
		}
	}
}

bool NextIsFood(pSnakeNode pn, pSnake ps)
{
	if (ps->_pFood->x == pn->x && ps->_pFood->y == pn->y) {
		return true;
	}
	else {
		return false;
	}
}

void EatFood(pSnakeNode pn, pSnake ps)
{
	//头插法
	ps->_pFood->next = ps->_pSnake;
	ps->_pSnake = ps->_pFood;

	//释放下一个位置的节点
	free(pn);
	pn = NULL;
	pSnakeNode cur = ps->_pSnake;
	//打印
	while (cur)
	{
		SetPos(cur->x, cur->y);
		wprintf(L"%lc", BODY);
		cur = cur->next;
	}

	ps->_score += ps->_food_weight;

	//重新创建食物
	CreateFood(ps);
}

void NoFood(pSnakeNode pn, pSnake ps)
{
	//头插法
	pn->next = ps->_pSnake;
	ps->_pSnake = pn;

	pSnakeNode cur = ps->_pSnake;
	while (cur->next->next != NULL)
	{
		SetPos(cur->x, cur->y);
		wprintf(L"%lc", BODY);
		cur = cur->next;
	}
	//把最后一个节点打印成空格
	SetPos(cur->next->x, cur->next->y);
	printf("  ");

	//释放最后一个节点
	free(cur->next);
	cur->next = NULL;
}

void KillByWall(pSnake ps)
{
	if (ps->_pSnake->x == 56 || ps->_pSnake->x == 0 || 
		ps->_pSnake->y == 0 || ps->_pSnake->y == 26)
		ps->_status = KILL_BY_WALL;
}

void KillBySelf(pSnake ps)
{
	pSnakeNode cur = ps->_pSnake->next;
	while (cur)
	{
		if (cur->x == ps->_pSnake->x && cur->y == ps->_pSnake->y) {
			ps->_status = KILL_BY_SELF;
			break;
		}
		cur = cur->next;
	}
}

void SnakeMove(pSnake ps)
{
	//创建一个节点，表示蛇即将到的下一个节点
	pSnakeNode pNextNode = (pSnakeNode)malloc(sizeof(SnakeNode));
	if (pNextNode == NULL) {
		perror("SnakeMove():malloc()");
		return;
	}
	switch (ps->_dir)
	{
	case UP:
		pNextNode->x = ps->_pSnake->x;
		pNextNode->y = ps->_pSnake->y - 1;
		break;
	case DOWN:
		pNextNode->x = ps->_pSnake->x;
		pNextNode->y = ps->_pSnake->y + 1;
		break;
	case LEFT:
		pNextNode->x = ps->_pSnake->x - 2;
		pNextNode->y = ps->_pSnake->y;
		break;
	case RIGHT:
		pNextNode->x = ps->_pSnake->x + 2;
		pNextNode->y = ps->_pSnake->y;
		break;
	}
	
	//检测下一个坐标处是否是食物
	if (NextIsFood(pNextNode, ps)) {
		EatFood(pNextNode, ps);
	}
	else {
		NoFood(pNextNode, ps);
	}

	//检测是否撞墙
	KillByWall(ps);

	//检测蛇是否撞到自己
	KillBySelf(ps);
}

void GameRun(pSnake ps)
{
	//打印帮助信息
	PrintHelpInfo();
	do
	{
		//打印总分数和食物的分值
		SetPos(64, 10);
		printf("总分数：%d\n", ps->_score);
		SetPos(64, 11);
		printf("当前食物的分数：%2d\n", ps->_food_weight);

		if (KEY_PRESS(VK_UP) && ps->_dir != DOWN)
		{
			ps->_dir = UP;
		}
		else if (KEY_PRESS(VK_DOWN) && ps->_dir != UP)
		{
			ps->_dir = DOWN;
		}
		else if (KEY_PRESS(VK_LEFT) && ps->_dir != RIGHT)
		{
			ps->_dir = LEFT;
		}
		else if (KEY_PRESS(VK_RIGHT) && ps->_dir != LEFT)
		{
			ps->_dir = RIGHT;
		}
		else if (KEY_PRESS(VK_SPACE))
		{
			//暂停
			Pause();
		}
		else if (KEY_PRESS(VK_F3))
		{
			//加速
			if (ps->_sleep_time > 80) {
				ps->_sleep_time -= 30;
				ps->_food_weight += 2;
			}
		}
		else if (KEY_PRESS(VK_F4))
		{
			//减速
			if (ps->_food_weight > 2)
			{
				ps->_sleep_time += 30;
				ps->_food_weight -= 2;
			}
		}
		else if (KEY_PRESS(VK_ESCAPE))
		{
			//正常退出游戏
			ps->_status = END_NORMAL;
		}

		SnakeMove(ps);
		Sleep(ps->_sleep_time);

	} while (ps->_status == OK);
}

void GameEnd(pSnake ps)
{
	SetPos(24, 12);
	switch (ps->_status)
	{
	case END_NORMAL:
		wprintf(L"您主动结束游戏\n");
		break;
	case KILL_BY_WALL:
		wprintf(L"您撞到了墙上，游戏结束\n");
		break;
	case KILL_BY_SELF:
		wprintf(L"您撞到了自己，游戏结束\n");
		break;
	}

	//释放蛇身的链表
	pSnakeNode cur = ps->_pSnake;
	while (cur)
	{
		pSnakeNode del = cur;
		cur = cur->next;
		free(del);
	}

}